A conventional receptacle used for an extension cord i with a plug 11 and an electric wire 12 shown in FIG. 7 includes a plurality of sockets 13 fitted in holes in an upper cap 14 and a bottom plate 15 combined with the cap 14 with a screw 16.
However, this conventional receptacle is considered to have the following drawbacks.
1. The upper cap and the bottom plate are made of plastic with a mold by injecting process, so a maker has to prepare a plurality of molds for making receptacles of different sizes and shapes, to a resultant high cost in manufacture.
2. The upper plate and the bottom plate are combined together with a screw, so a driver has to be used in case of checking the receptacle or fixing electric wires on it.